1. Field of the Invention
This invention relates to a cutting carriage for sheet cutting used in a copier, a facsimile machine, a printer or the like, and also relates to a sheet cutter using such a carriage.
2. Related Art
One example of conventional sheet cutters, mounted on a recording apparatus such as a copier, a printer and a facsimile machine, is a so-called rotary-type cutter as disclosed in Japanese Patent Examined Publication No. 50-24466, in which two blades, having a width corresponding to a cutting width, are provided, and one of the two blades is rotated, and is brought into press-contact with the other blade in intersecting relation thereto, thereby cutting a sheet.
Another conventional sheet cutter is a so-called Guillotine-type sheet cutter as disclosed in Japanese Utility Model Examined Publication No. 58-37594, in which two blades, having a width corresponding to a cutting width, are provided, and one of the two blades is moved vertically (upward and downward), and is brought into sliding contact with the other blade, thereby cutting a sheet.
These cutters have an advantage that the sheet can be cut rapidly since there are used the two blades having the width corresponding to the cutting width.
These cutters have an advantage that the cutting speed is high since there are used the two blades having the width corresponding to the cutting width. However, the blades are large in size, and therefore there has been encountered a problem that a load required for driving the blade is large.
Under the circumstances, there has been proposed a sheet cutter of the blade moving-type as disclosed in Japanese Utility Model Unexamined Publication Nos. 4-128195 and 3-88688, in which a circular blade or a knife edge blade is moved in sliding contact with a stationary blade, having a substantially straight cutting edge extending in a direction of a cutting width of a sheet, thereby cutting the sheet.
In this sheet cutter of the blade moving-type, the blade itself is moved, and the size of the moving blade is not limited by the cutting width, and can be small, and therefore there is an advantage that a load, required for driving the blade, is smaller as compared with the load required in the above rotary-type and Guillotine-type cutters. Therefore, the sheet cutter of the blade moving-type is advantageous in that the sheet cutter itself can be formed into a small size.
Japanese Patent Unexamined Publication Nos. 7-52085, 7-24782, 5-177585, 2-250793 and 8-57797 and Japanese Utility Model Unexamined Publication No. 1-149286 disclose a sheet cutter of the blade moving-type in which instead of using a stationary blade, a pair of circular blades are combined together in press-contact with each other, and the pair of circular blades are moved in a cutting direction, thereby cutting a sheet by the press-contacted portions of the two circular blades.
In this sheet cutter of the blade-moving type, there is no need to provide a stationary blade having a length corresponding to the cutting width, and therefore this construction is advantageous in that the size of the sheet cutter can be further reduced.
The above sheet cutter of the blade moving-type can be of a smaller size, and therefore it is advantageous to incorporate this type of sheet cutter in an office automation machine, such as a copier, a facsimile machine and a printer, which is required to have a space-saving design.
In such a blade-moving type sheet cutter, regardless of whether it is the type of sheet cutter using a stationary blade or the type of sheet cutter having a pair of rotary blades movable in a cutting direction, there is needed a carriage which supports the blade, and is movable in a cutting direction.
In connection with a blade moving-type sheet cutter using a stationary blade, Japanese Patent Unexamined Publication No. 7-124892 discloses a carriage having a bearing mechanism rotatably supporting a circular blade (rotary blade).
This publication also discloses a carriage in which a roller is provided coaxially with the rotary blade, and the roller is brought into contact with the stationary blade to thereby forcibly rotate the rotary blade.
The inventor of the present invention has studied these cutting carriages incorporating the rotary blade, and has found a problem that positional accuracy or precision is lowered by a clearance between a guide rail (guide track member) and the carriage during the cutting operation.
More specifically, because of a very small gap or clearance, a defective cut portion is produced, and the blade deviates from a straight line along which the cutting is to be effected, thereby lowering the accuracy or precision.